@madbrewlabs: the best place to keep up with those developments is on the Free RPG Community.

@Ricardo: Many thanks again. You're demonstrating the benefit of having a community of us free creators, we can offer friendly and informed advice. I have updated the post to include your comment as a quote for those scared of reading comments!

Rob: Again, thanks for the shout out for the Free RPG Community, we appreciate it. Again, I'm going to play the pedant but here are some notes:

Product Identity (PI) is actually a form of super-trademark, as opposed to copyright. That is, it allows you to protect certain terms, as well as other concepts and ideas (not normally covered by trademark or copyright). In an OGL work there are typically four types of protection: traditional copyright, OGC, trademarks and PI.